Suture anchors have been developed for anchoring sutures in endoscopic or arthroscopic surgery through single sided access. Most prior art suture anchors are delivered from a lumen of a needle or a tubular device. Prior art include U.S. Pat. No. 4,235,238 by H. Ogiu et al., issued on Nov. 25, 1980, U.S. Pat. No. 4,741,330 by J. Hayhurst, issued on May 3, 1988, U.S. Pat. No. 4,669,473 by W. Richards et al., issued on Jun. 2, 1987, U.S. Pat. No. 5,800,445 by K. Ratcliff et al., issued on Sep. 1, 1998; U.S. Pat. No. 5,041,129 by J. Hayhurst et al., issued on Aug. 20, 1991, U.S. Pat. No. 5,845,645 by P. Bonutti, issued on Dec. 8, 1998, U.S. Pat. RE36,974, reissued on Nov. 28, 2000, and U.S. Pat. No. 6,312,448 by P. Bonutti, issued on Nov. 6, 2001. Since the anchors reside within the lumen of the delivery device, the size of the needles or tubular members is correspondingly larger, making tissue penetration more difficult and traumatic.
Several prior art anchors reside outside and around a needle. For delivery, a push rod is used to push along one side of the suture anchor, sliding along the needle into the tissue. A suture connected at the opposite side of the push rod is used to pull the anchor as the anchor is being pushed by the push rod. A series of patents by P. Bonutti, U.S. Pat. No. 5,814,072, issued on Sep. 29, 1998, U.S. Pat. No. 5,948,002, issued on Sep. 7, 1999, U.S. Pat. No. 6,033,430, issued on Mar. 7, 2000 and U.S. patent application publication No. 2001/0002440, publication date: May 31, 2001, proposed the push and pull method to pivot the anchor within tissue. Pivoting of an anchor within tissue is classified as partial-thickness suture fastening. To facilitate instant pivoting, the suture is connected close to both distal and proximal ends of the anchor to provide favorable leverage for anchor rotation. FIG. 1 depicts the prior art 235, which has completed the rotation within tissue. The suture 122 is looped near or at both ends of the anchor 235, as depicted in the prior art patents. For favorable leverage, the strands of suture 122 connected to the anchor 235 are widely spaced apart. As tension is applied to the suture 122, the strands of suture 122 spread open, as indicated by the shaded area 236, opening or pushing out the tissue 130 along the path of anchor 235 entry. Especially within soft tissue, the widely spaced sutures 122 wedge open the tissue directly above the anchor 235. As a result, the pullout strength of the anchor 235 is likely to be low. The probable mode of failure is likely to be anchor 235 pullout, as depicted in FIG. 2, rather than suture 122 breakage. While the widely spaced suture 122 provides favorable leverage for rapid rotation, it appears to sacrifice the strength of tissue anchoring.
Another prior art suture anchor, U.S. Pat. No. 5,626,614 by C. Hart, issued on May 6, 1997, also resides outside and around a needle. Hart's invention is designed for fastening or proximating tissues separated by two distinct walls, such as the stomach and abdominal walls, using full-thickness fastening. Unfortunately, most tissue within the body adheres to adjacent tissue with no clear separation, space or cavity. Therefore, full-thickness anchor pivoting to fasten or proximate two tissues has limited use.